physiology in pregnancy lecture

Definition of fertilazation

Fertilization is defined as the course of combination of the oocyte and sperm

It onset 12h after ovulation usually in ampulla of the oviduct(fallopian tube)

Definition of pregnancy

Pregnancy is defined as the course of embryo and fetal growth and development in uterine

It begin at the fertilization and end the delivery of the fetal and it’s attachment

Normal Pregnancy

Pregnancy The course that the embryo and the

fetus grow in the maternal body Stages of pregnancy1. Early pregnancy: ≤12 weeks2. Mid pregnancy: ≥13 weeks,≤27 weeks 3. Late pregnancy:≥28 weeks4. Term pregnancy:≥37 weeks,<42

weeks

Formation of Embryo

Fertilization1. Place: oviduct (ampulla)2. Process capacitation → acrosome

reaction→ penetrate the zona pellucida→ second meiosis →zygote

Formation of Embryo

Implantation1. requirement1) Disappear of zona pellucida

2) Formation of syncytiotrophoblast3) Synchronized development of

blastocyst and endometrium4) Adequate progesterone

Formation of Embryo

2. Process1) morula (day 3) → enter uterine

cavity (day 4) → early blastocyst→ late blastocyst (day 6-7) → implantation

2) location→ adherence→ penetration

Development of embryo and fetus

Definition1. embryo: ≤ 8 weeks2. Fetus: ≥ 9 weeks, human shape

Development of embryo and fetus

Physiology of fetus1. Circulation1) fetus ←→placenta←→ mater2) 1 umbilical vein (full of oxygen), 2

umbilical artery (lack of oxygen)3) Mixed blood (vein and artery)

Development of embryo and fetus

Development of embryo and fetus

2. Hematology1) ErythropoiesisFrom yolk sac: 3 weeksFrom liver: 10 weeksFrom bone marrow and spleen: term

(90%)EPO production: 32nd week

Development of embryo and fetus

2) Fetal hemoglobinFetal hemoglobin: early pregnancyAdult hemoglobin: 32nd weekTerm: fetal type Hb 25%3) White cellsLeukocytes: 8 weekLymphocytes (antibody production): 12

week, thymus and spleen

Development of embryo and fetus

3. Gastrointestinal tract1) drink amniotic fluid: 4th month2) no proteolytic activity3) enzymatic deficiencies in liver: bilirubin is not easy to be clear.

Development of embryo and fetus

4. Kidney Its function begins at 11-14th week5) Endocrinology6) Fetal thyroid: the first endocrine gland

(6th week), synthesize thyroxine at 12th week

7) Fetal adrenal cortex: widen (20th week), a fetal zone. synthesize steroid hormones (E3, liver placenta mater)

Placenta

Structure1. Primary villus syncytiotrophoblast cytotrophoblast2. Secondary villus3. third class vilusfetal capillary enter the stroma

Structure of placenta

Round Weight:450-650g Diameter:16-20cm Thickness:1-3cm thick in center and thin in margin

Placenta

Function1. metabolism1) Exchange of O2 and CO2

2) Exchange of nutritive factors and waste

2. DefensiveLimited. IgG, virus, drug

Placenta

3. Endocrine1) HCG2) HPL3) E4) P5) Oxytocinase6) Cytokines and Growth Factors4. Immunity tolerance

Fetal membranes

Structure chorion and amnion Amnion A double-layered translucent

membrane Become distended with fluid

Umbilical Cord

Structure amnion, yolk sac, one vein, two

artery and Wharton jelly Length 30-70cm

Amniotic fluid

Source1. exudation of fetal membranes

(early pregnancy)2. Fetal urine3. Fetal lung4. Exudation of amnion and fetal skin

Volume of amniotic fluid 8 weeks:5-10ml

10 weeks:30ml

20 weeks:400ml

38 weeks:1000ml

Amniotic fluid

Absorb1. Fetal membrane2. Umbilical cord3. Fetal skin4. Fetal drinking Feature1000-1500ml at 36th-38th week (peak),

transparent → slightly turbid

Amniotic fluid

Function1. Protect fetal move freely, warm2. Protect mater prevent infection

Maternal changes during pregnancy

The maternal system may produce a series of changes in order to adapt to the needing of fetal growth and development influenceed by placenta hormone and neuro-endocrine

Physiologic changes in pregnant woman

Genital organs1. Uterus1) capacity: 5ml-5000ml.weight: 50g-

1000g2) Hypertrophy of muscle cells3) Endometrium→decidua: basal decidua,

capsular decidua, true decidua4) Contraction: Braxton Hicks5) Isthmus uteri: 1cm→ 7-10cm

Physiologic changes in pregnant woman

6) Cervix: colored7) Ovary: placenta replaces ovary (10th

week)8) Vagina: dilated and soft, pH↓(anti-

bacteri bacteria)9) Ligaments: relaxed

Physiologic changes in pregnant woman

Cardiovascular system1. Heart: move upward, hypertrophy of cardiac

muscle2. Cardiac Output increase by 30%, reach to peak at

32nd –34th week3. Blood pressure early or mid pregnancy Bp↓.late

pregnancy Bp↑ .Supine hypotensive syndrome

Physiologic changes in pregnant woman

Hematology1. Blood volume1) Increase by 30%-45% at 32nd –34th (peak)2) Relatively diluted2. Composition1) Red cells Hb:130→110g/L, HCT:38%→ 31%.2) White cells: slightly increase3) Coagulating power of blood: ↑ 4) Albumin: ↓,35 g/L

Physiologic changes in pregnant woman

The Respiratory system1. R rate: slightly ↑2. vital capacity: no change3. Tidal volume: ↑ 40%4. Functional residual capacity:↓ 5. O2 consumption: ↑ 20%

Physiologic changes in pregnant woman

The urinary system1. Kidney1) Renal plasma flow (RFP):↑35%2) Glomerular filtration rate (GFR):↑ 50%2. Ureter Dilated (P↑)3. Bladder Frequent micturation

Physiologic changes in pregnant woman

Gastrointestinal system1) Gastric emptying time is

prolonged→ nausea. 2) The motility of large bowel is

diminished → constipation3) Liver function: unchanged

Physiologic changes in pregnant woman

Endocrine1. Pituitary (hypertrophy)1) LH/FSH: ↓2) PRL:↑3) TSH and ACTH:↑2. Thyroid1) enlarged (TSH and HCG↑)2) thyroxine↑ and TBG↑ → free T3 T4

unchanged

Metabolism

Basal metabolism rate, BMR +15-20% Weight gain 12.5 Fetus 3400 g Placenta 650 g Amniotic 800 g Uterus 960 g Plasma, red cells 1450 g Mammary glands 405 g Extracellular, extravascular water 1480 g Deposition of fat and protein 3345 g Insulin resistance

Weight Gain in Pregnancy - Physiology 27.5 lbs (12.5 kg) is “normal”

physiologic gain (Hytten 1991) 9 kg (~20 lbs) is made up of fetus,

placenta, amniotic fluid, uterine/breast hypertrophy, increased blood volume and retained fluid

3.5 kg (7.5 lbs) is maternal storage fat